Catheter-based procedures are commonly used in medical practice to treat regions within the body that are not easily accessible by surgery or wherein access without surgery is desirable. In one catheter-based procedure, a prosthetic valve is delivered to a human heart using a percutaneous approach for replacing a defective native heart valve. Although the replacement of native heart valves using percutaneously delivered prosthetic valves has shown great potential, the effectiveness of this procedure is often limited by the operator's ability to navigate through the patient's vasculature, such as through small vessels and around the aortic arch.
In one delivery method, a prosthetic valve is mounted on a balloon catheter. Before advancing the prosthetic valve to the heart, a guide sheath is introduced into the iliac artery of the patient. Although the guide sheath adds diameter and complexity to the system, the guide sheath is necessary for advancing the catheter and prosthetic valve through the relatively narrow arterial vessels. The balloon catheter and prosthetic valve are pushed by the operator through the guide sheath to the treatment site. In one shortcoming of this procedure, the balloon catheter may lack the pushability required to be effectively advanced through the guide sheath. Furthermore, after exiting the guide sheath, the prosthetic valve may come into contact with the inner wall of the vessel, such as along the aortic arch. As a result of this contact, the vessel wall may be damaged and advancement of the prosthetic valve may be impeded or prevented altogether. Furthermore, calcification and plaque can be dislodged from the vessel wall.
Due to the shortcomings associated with existing delivery systems, there is a need for a new and improved delivery system that may be used to deliver a prosthetic valve to a human heart in a safe and effective manner. It is desirable that such a system does not require the use of a conventional guide sheath. It is also desirable that such a system eases the tracking process and reduces the displacement of plaque or calcification along the inner walls of the body vessels. It is also desirable that such a system has sufficient flexibility to track through the curves of a body vessel, while providing sufficient pushability to ensure that the prosthetic valve can be tracked to the native valve site. It is desirable that such a system also provides a means for deploying the prosthetic valve at the native valve site in a controlled and precise manner. The present invention addresses this need.